The B2B question

[Ava the Adria]

I don't know enough about smart alternators to tell you if there is some kind of fault and maybe it shouldn't be doing this. But if it is working as intended, then there is a solution.

You want the B2B to come on if the engine is running AND the voltage is above a threshold, say 13.5V. The B2B starts working as soon as it gets a signal on the D+ input. So, you could put a relay in the D+ signal path, with the coil triggered by a voltage-sensitive relay (VSR) with a suitable threshold voltage. The VSR should be connected to the starter battery, so it senses the alternator output voltage.

As the Alternator voltage rises, the VSR switches on the D+ signal, activating the B2B if the engine is running. when the alternator voltage falls, the VSR switches off the D+ signal, so the B2B is inactivated.

If for some reason (eg solar power) the starter battery voltage rises when the engine isn't running, the VSR will trigger, but there is no D+ signal so the B2B won't be activated.

The VSR and the other standard relay would be switching a coil and the D+ signal, so they can both be low power, they don't have to be high power types.

I think you are right, and I think that smart alternator isn't working properly. If the B2B turns on, the alternator should provide power to it, even if it is at a low voltage. But the Ava the Adria says it doesn't, and the B2B takes power from the starter battery, causing it to discharge. The arrangement I described,with the VSR on the D+, would stop that happening, but as you say it doesn't solve the underlying problem.

Thanks for all the suggestions, esp around controlling the D+. Probably need to investigate what’s going on with the alternator output (especially the delay until it’s revved up) to see if it’s smart or if there’s a fault there. Also to check out whether we have a proper D+ or just an ignition live. Then we can manage where we go from there.

 

[autorouter]

Also to check out whether we have a proper D+ or just an ignition live. Then we can manage where we go from there.

The way I think of it, when you turn the key, the dash lights come on. That's the Ignition. When the engine starts, the alternator light goes off. That's the D+.

 

[Raul]

If you have a smart alternator, look for a shunt on the -ve starter battery post. If it’s there, you have a smart alternator. The way to connect the B2B is AFTER that shunt, on the chassis for example, so the ecu sees a draw and engage the alternator.
Some ppl make the mistake and connect the B2B from the starter battery. In this situation, the current to the B2B does not flow trough the shunt anymore, and ecu can’t see it, therefore will not turn on the alternator soon enough. Check this to.

 

[Pausim]

I think it unlikely that Ava the Adria has a smart alternator because Fiat were still supplying motorhome constructors with disabled ones in 2017. It seems he may have an ignition feed not a D+ one.

 

[Portland]

I have just had problems with the charging system which is the Shaudt 220-B ELB coupled to the DT220 control panel. The ELB was refurbished by Appuljack plus the panel was checked, when refitted I had all sorts of anomalies but with the help of Ross at Appuljack this was sorted, however it seems this combination is not the best and is easily confused by the B2B which will result with it needing to be reset quite often. So I have disconnected the B2B but wonder if there is a way to fix it.

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[autorouter]

I think it unlikely that @Ava the Adria has a smart alternator because Fiat were still supplying motorhome constructors with disabled ones in 2017. It seems he may have an ignition feed not a D+ one.

If there's no D+ signal available, it might be worth thinking about a Votronic D+ simulator, which works from by sensing engine vibrations.

D+ Simulator Pro_3067 | VOTRONIC

www.votronic.de

Reading the description, it looks like for a Euro6 engine you'd need the Pro version.

 

[autorouter]

I have just had problems with the charging system which is the Shaudt 220-B ELB coupled to the DT220 control panel. The ELB was refurbished by Appuljack plus the panel was checked, when refitted I had all sorts of anomalies but with the help of Ross at Appuljack this was sorted, however it seems this combination is not the best and is easily confused by the B2B which will result with it needing to be reset quite often. So I have disconnected the B2B but wonder if there is a way to fix it.

Which B2B is fitted? Is it an add-on or fitted in the original setup? Is it connected to the batteries directly, or does it go through the EBL?

 

[Portland]

It's a Vicron coupled to direct to the batteries as the ELB doesn't have a connection, to my knowledge.

 

[autorouter]

however it seems this combination is not the best and is easily confused by the B2B which will result with it needing to be reset quite often.

What has to be reset often? Is it only the State Of Charge (SOC), ie the % Remaining), or is it other things as well?

 

[Portland]

It seems the DT220 control panel cannot manage to cope with the fluctuations over time, it begins to show incorrect information (information direct from Apuljack) so you have to reset the panel to the correct settings, not always easy with this combination, however if you put in the correct code for the make it can be done

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[autorouter]

It seems the DT220 control panel cannot manage to cope with the fluctuations over time, it begins to show incorrect information (information direct from Apuljack) so you have to reset the panel to the correct settings, not always easy with this combination, however if you put in the correct code for the make it can be done

To measure the battery amps, the EBL contains a shunt resistor, and all the amps flowing into or out of the leisure battery is supposed to flow through that shunt. The panel keeps track of the amps going into or out of the battery over time, so it always knows the state of charge (SOC) of the battery. You tell it the size of the battery, and tell it when it's 100% full, and from that time the panel can tell you the percentage SOC.

That's the theory. But if there are other paths for the amps in/out of the battery then the EBL can't account for that, so the SOC figure becomes inaccurate. The voltage figures are not affected, and are still accurate.

You can just ignore the SOC % figure, and live with it. Another possibility is to fit a proper battery monitor. Usually that involves fitting a 'shunt' in the negative wire right next to the battery. Then a run a data cable from the shunt to a display unit mounted in a convenient place. You can even get a 'SmartShunt' which fits near the negative terminal and transmits data via Bluetooth to an App on your phone - no data cable needed.

Examples are NASA BM-1, Victron BMV712 or Victron SmartShunt.

 

[ChrisL]

It seems the DT220 control panel cannot manage to cope with the fluctuations over time, it begins to show incorrect information (information direct from Apuljack) so you have to reset the panel to the correct settings, not always easy with this combination, however if you put in the correct code for the make it can be done

Have you had lithium batteries fitted? If so your state of charge may not be accurate if it is measured by battery voltage because lithium batteries voltage stays stable until the batteries are almost flat.

 

[Pausim]

Have you had lithium batteries fitted? If so your state of charge may not be accurate if it is measured by battery voltage because lithium batteries voltage stays stable until the batteries are almost flat.

With Lithium the battery monitor needs to be adjusted for a different level of efficiency and lower Peukerts exponent, as well as different settings for automatic synchronisation. The only battery monitors I could find that allowed this were the Victron BMV series. The Nasa one seemed to cope with anomalies by coming up with nonsense readings like 104% full.

 

[Adriaadventure]

The NE237 unit does indeed have a 70A 'split charge' relay built in which is activated by the D+ signal.
If you look at the suggested wiring diagrams for the Votronoic B-B unit you will see that you can fit the votronic B-B ( 12v 30A model ) in series with the NE237 using all existing cables ( with very little modification ) and your existing display shows the charge/discharge current including any solar panel gains as the shunt is inside the NE237.
( I also changed to an MPPT solar controller which is connected by a plug into an existing socket on top of the NE237 which is provided for this purpose and has the advantage of making the charge current visible because it goes through the shunt and is therefore shown on the display panel.)
The D+ signal is available by teeing into a connector on top of the Ne237 unit.

I have done this upgrade using the votronic BtoB 12/30 duo and recently upgraded to a Lithium battery. Works perfectly charging at 30A ( 15A ish with the fridge/freezer taking approx 15A ).

 

[Ava the Adria]

The NE237 unit does indeed have a 70A 'split charge' relay built in which is activated by the D+ signal.
If you look at the suggested wiring diagrams for the Votronoic B-B unit you will see that you can fit the votronic B-B ( 12v 30A model ) in series with the NE237 using all existing cables ( with very little modification ) and your existing display shows the charge/discharge current including any solar panel gains as the shunt is inside the NE237.
( I also changed to an MPPT solar controller which is connected by a plug into an existing socket on top of the NE237 which is provided for this purpose and has the advantage of making the charge current visible because it goes through the shunt and is therefore shown on the display panel.)
The D+ signal is available by teeing into a connector on top of the Ne237 unit.

I have done this upgrade using the votronic BtoB 12/30 duo and recently upgraded to a Lithium battery. Works perfectly charging at 30A ( 15A ish with the fridge/freezer taking approx 15A ).

That is really interesting, thank you for taking the time to reply.
When we first installed the lithiums I had purchased that same 30A Votronic B2B to go in with them and was talked out of it by the workshop fitting the batteries, inverter and B2B! They sold me the Renogy 40A (which of course they had in stock…) on the basis 30A wasn’t enough charge power. It’s now in a cupboard in the garage somewhere. Overlooked it for the new Sterling as that was more powerful and had starter bat maintenance. But I’m beginning to think we may have got it right first time!
(We also have a Votronic inverter, solar mppt controller, shunt and battery monitor, so it may be time to dig it out)!

If there's no D+ signal available, it might be worth thinking about a Votronic D+ simulator, which works from by sensing engine vibrations.

D+ Simulator Pro_3067 | VOTRONIC

www.votronic.de

Reading the description, it looks like for a Euro6 engine you'd need the Pro version.

I visited the van yesterday (but didn’t take the multimeter ). We do appear to have a proper D+ signal into the NE237 and existing B2B - ignition on, nothing powered up (only dash lights). Engine on, B2B lights up as does the charge light on the display panel. Does make me wonder what’s been causing the starter battery to discharge so much in the time before the alternator “wakes up” after starting the engine. We fitted a new starter battery after that incident in Paderborn, but even the new one is suffering significant discharges when the engine first starts up before the alternator kicks in. Will have to check this out when the van goes to the electricians this week.

So the question now is which of our b2bs to ask them to fit and how to wire it in? The Renogy is only D+ on or off and has previous (in our set up) for draining a starter battery to death. Reading the Votronic manual, that has D+ and a low voltage switch off, the Sterling also has D+ with low voltage sensing switch off.

Running the B2B through the NE237 as in the Votronic circuit diagram seems to make sense, it does have a 70A internal relay from the B1 and should easily cope with 30A. We also wouldn’t then need to fit the NC (isolation) relay into the NE237 D+ feed.
Although as you do say, you lose 15A or so to the fridge, ours can run on gas if we needed to maximize the charge going into the hab batteries say on short journeys between stops (European spec LHD Adria with crash sensor gas valve). That’s not an issue in the UK, where everywhere seems to have EHU and we tend to drive further between Aires in the EU (and the solar is stronger). The supply cable size from starter bat has been ok with the 40A Renogy so either are well within scope. A plus of the Votronic unit is that it does offer a bridging cable facility to maintain the starter battery although the Sterling seems to have significantly more powerful starter battery charging, as already discussed.
(We have a separate shunt on the habitation negative (which everything including the inverter goes through) to a stand alone (Votronic) battery monitor bulkhead display, the onboard NE237 shunt for battery SoC is pretty much redundant already).

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[Adriaadventure]

That is really interesting, thank you for taking the time to reply.
When we first installed the lithiums I had purchased that same 30A Votronic B2B to go in with them and was talked out of it by the workshop fitting the batteries, inverter and B2B! They sold me the Renogy 40A (which of course they had in stock…) on the basis 30A wasn’t enough charge power. It’s now in a cupboard in the garage somewhere. Overlooked it for the new Sterling as that was more powerful and had starter bat maintenance. But I’m beginning to think we may have got it right first time!
(We also have a Votronic inverter, solar mppt controller, shunt and battery monitor, so it may be time to dig it out)!

I visited the van yesterday (but didn’t take the multimeter ). We do appear to have a proper D+ signal into the NE237 and existing B2B - ignition on, nothing powered up (only dash lights). Engine on, B2B lights up as does the charge light on the display panel. Does make me wonder what’s been causing the starter battery to discharge so much in the time before the alternator “wakes up” after starting the engine. We fitted a new starter battery after that incident in Paderborn, but even the new one is suffering significant discharges when the engine first starts up before the alternator kicks in. Will have to check this out when the van goes to the electricians this week.

So the question now is which of our b2bs to ask them to fit and how to wire it in? The Renogy is only D+ on or off and has previous (in our set up) for draining a starter battery to death. Reading the Votronic manual, that has D+ and a low voltage switch off, the Sterling also has D+ with low voltage sensing switch off.

Running the B2B through the NE237 as in the Votronic circuit diagram seems to make sense, it does have a 70A internal relay from the B1 and should easily cope with 30A. We also wouldn’t then need to fit the NC (isolation) relay into the NE237 D+ feed.
Although as you do say, you lose 15A or so to the fridge, ours can run on gas if we needed to maximize the charge going into the hab batteries say on short journeys between stops (European spec LHD Adria with crash sensor gas valve). That’s not an issue in the UK, where everywhere seems to have EHU and we tend to drive further between Aires in the EU (and the solar is stronger). The supply cable size from starter bat has been ok with the 40A Renogy so either are well within scope. A plus of the Votronic unit is that it does offer a bridging cable facility to maintain the starter battery although the Sterling seems to have significantly more powerful starter battery charging, as already discussed.
(We have a separate shunt on the habitation negative (which everything including the inverter goes through) to a stand alone (Votronic) battery monitor bulkhead display, the onboard NE237 shunt for battery SoC is pretty much redundant already).

 

[Adriaadventure]

Do you by any chance have a 'comfortmatic' gearbox as the system uses a lot of amps from the start battery when you first turn on the ignition ( or even open the drivers door with the ignition off ! ) to pressurise the system ready for gear selection.
Just opening the door sometimes causes a low start battery voltage alarm for a few seconds on ours.

 

[Ava the Adria]

Do you by any chance have a 'comfortmatic' gearbox as the system uses a lot of amps from the start battery when you first turn on the ignition ( or even open the drivers door with the ignition off ! ) to pressurise the system ready for gear selection.
Just opening the door sometimes causes a low start battery voltage alarm for a few seconds on ours.

Hi,
We’re 6 speed manual, 150bhp.

They checked the alternator - all working correctly, it’s not Euro6. The D+ is D+, not ignition live, so the 30A b2b been wired as per the Votronic diagram you suggested, to go through the NE237 with the jumper wire for the starter battery connected. Hopefully the NE237 can cope with 30A, perhaps 40A from the Renogy was too much for it.
They weren’t worried about the voltage drop on starting, saying the amps were up where they should be apparently!